#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
double fact(int n) {
	if (n == 1) {
		return 1;
	}
	else {
		return n * fact(n - 1);
	}

}
int main() {
	int m, n;
	double ret;
	while (scanf("%d %d", &m, &n) != EOF) {
		if (m >= n) {
			ret = fact(m) / (fact(n) * fact(m - n));
			printf("%.0lf\n", ret);
		}
	}
	return 0;
}